Electrical logic operations are the building blocks of digital circuits. Aside from transistors, there are a number of device technologies that are able to perform logic operations including diodes, resistors, relays, and vacuum tubes. None of these technologies, however, have practical applications in integrated circuits (ICs) due to limitations in scaling and fabrication and/or the ability to perform signal gain. Thus, the transistor is the device typically used in digital circuits for performing logic operations, particularly when fabricated as complementary metal oxide semiconductor (CMOS) circuitry on an IC. CMOS logic, however, is approaching limits in terms of scaling and energy efficiency.